<!doctype html>
<html>
<title>Lazyload images cannot load immediately from the list of available images if their tuple doesn't match other images in that list</title>
<link rel="author" title="Dom Farolino" href="mailto:dom@chromium.org">
<link rel="author" title="Przemyslaw Gorszkowski" href="mailto:pgorszkowski@igalia.com">
<link rel="help" href="https://html.spec.whatwg.org/multipage/images.html#updating-the-image-data">
<link rel="help" href="https://html.spec.whatwg.org/multipage/urls-and-fetching.html#cors-settings-attribute">
<script src="/resources/testharness.js"></script>
<script src="/resources/testharnessreport.js"></script>

<!-- A `loading=lazy` image will be placed below this div so that it is below
     the viewport -->
<div id="img-container"></div>
<div style="height: 1000vh;"></div>
<div id="below-viewport-img-container"></div>

<script>
const image_path = 'resources/image.png?image-lazy-loading-lazy-different-crossorigin-' + Math.random();

promise_test(async t => {
  await new Promise((resolve, reject) => {
    const img = new Image();
    img.onload = resolve;
    img.onerror = e => { reject(new Error("The img should not fail to load")) };
    document.querySelector('#img-container').append(img);
    img.src = image_path;
  });


  // At this point, the image fetched eagerly above exists in the "list of
  // available images". As per the spec's #updating-the-image-data algorithm [1]
  // step 6, the "list of avalable images" is consulted before we take any
  // lazyload-specific action. This means that lazyload images can load eagerly
  // if they target a resource in the list of available images (includes cors
  // settings attribute matching [2]). The image from "img-container" does not
  // have "crossorigin" attribute and the lazyload image has crossorigin="anonymous".
  // This means that lazyload image cannot be loaded eagerly from the list of available images.
  // [1]: https://html.spec.whatwg.org/multipage/images.html#updating-the-image-data
  // [2]: https://html.spec.whatwg.org/multipage/urls-and-fetching.html#cors-settings-attribute
  const lazyload_image_promise = new Promise((resolve, reject) => {
    const img = new Image();
    img.loading = 'lazy';
    img.crossOrigin = "anonymous";
    img.onload = e => {
      reject("The img should not be loaded from the list of available images because of different 'crossorigin'") };
    img.onerror = e => { reject("The img should not fail to load") };

    document.querySelector('#below-viewport-img-container').append(img);
    img.src = image_path;
  });
  const timeout_promise = new Promise((resolve, reject) => {
    t.step_timeout(() => {
      resolve("The `loading=lazy` image should not load immediately from " +
              "the list of available images because of different 'crossorigin'");
    }, 2000);
  });

  // The `timeout_promise` should resolve first because lazyload image is not
  // able to eagerly use resource from the "list of available images" if there
  // is a difference in 'crossorigin'.
  await Promise.race([lazyload_image_promise, timeout_promise]);
}, "Lazyload images cannot load immediately from the list of available images if their tuple doesn't match other images in that list");
</script>
